Previously I was just using a small, rear-facing 10" sealed box for the enclosure and for the most part it did the job. However, it never really sounded "right." I had to do all sorts of tuning with the HU EQ and finally after I reversed the input phase at the box things started to sound pretty good up in the driver area, but I knew the sound could be improved and I really wanted my whole trunk area available for cargo.

I have heard over many hours of thread surfing here about the potential advantages of a corner sub box compared to the standard F or R facing trapezoidal/rectangular mdf boxes, and I was determined to eventually get a hold of one. The problem seemed to be that they were hard to get a hold of because they're only produced by a couple of vendors out there, and those vendors either were extremely busy (read: hard to get a hold of), or for ones available directly online or ebay they seemed overpriced, at least to me.

Finally I lucked out and e46silverride showed up on the forum. I decided to be one of the guinea pigs for his first E90 boxes. He built it to my specs (sealed, net volume, and correct depth for my sub) and made a very fine quality product. Here's a link to his build thread: Here

I had no idea what to expect, but I have to say after having tested it for a week: he builds a great box.

It goes in on the passenger side above the battery tray and the fit was perfect. I'm willing to bet that it would stay put but I used some industrial velcro on the back just for insurance. The carpet color is very close to stock though I actually didn't care if it was exact or not. The subwoofer fit perfectly with enough depth for the speaker wire connections but no unnecessary excess (after all, I didn't want this thing sticking out and taking up trunk *******. The only modification I made to it was probably not needed, but I sprayed some plastidip inside and on the back on any bare glass or connection area mostly for my own security. I've read that any leaks no matter how tiny will impact the SQ in a sealed enclosure.

Now, for the sound. I'm comparing this to a small, sealed rear-facing enclosure and having made no further adjustments at all to the EQ or phase it sounds greatly improved over the old setup. The bass pervades the cabin and I can't find any dead spots when I lean forward or backward. It sounds equally good up front as in the back. At the same levels, it is definitely louder or at least more full sounding than the previous box.

Overall, I'm extremely pleased with the setup. e46silverride was a great guy to deal with and his work is very high quality. Hit him up if you're interested in picking up one of his E90 boxes!

Feel free to ask him any questions you have about availability and/or pricing.

Awesome looking box. How much to build one for a 12" RF Punch stage 3 subwoofer? I am guessing it may to be large of driver to make it work, but just thought I would ask. I am looking at putting it in a sealed enclosure.

The absolute best combination of enclosure volume and modeled subwoofer output (that I have been able to find so far), is 0.85 cu ft for an Image Dynamics IDmax10. This would also be the best sounding subwoofer, no doubt. A good budget alternative seems to be the Alpine Type R 12, which can work well in as little as 0.85 cu ft (getting close to the output if the IDmax10), but would be even better at 1.2 cu ft.

The absolute best combination of enclosure volume and modeled subwoofer output (that I have been able to find so far), is 0.85 cu ft for an Image Dynamics IDmax10. This would also be the best sounding subwoofer, no doubt. A good budget alternative seems to be the Alpine Type R 12, which can work well in as little as 0.85 cu ft (getting close to the output if the IDmax10), but would be even better at 1.2 cu ft.

What is it about the ID10 that everyone loves so much? I haven't had the change to listen to one yet. I will say that the 10w6v3 sounds incredibly responsive and accurate to my admittedly non-audiophile ears, but then again, they sound is a matter of preference and at one point in time I "preferred" a 15" Kicker L7.

Awesome looking box. How much to build one for a 12" RF Punch stage 3 subwoofer? I am guessing it may to be large of driver to make it work, but just thought I would ask. I am looking at putting it in a sealed enclosure.

That RF sub you mentioned looks like it actually has a shallower top mounting depth than the 10w6 I'm using. Contact the builder. I'm sure he can sort one out for you.

I have not tried the reverse polarity, will it do any harm to my amp or sub? My new JL 12W3V3 corner loaded sub sounds soft (powered by new JL 600/1 amp half way on the gain, crossed at 100Hz at 12db slope). Any advice appreciated. Is the reverse polarity for corner loaded enclosure - the common setup?

I was running 2 Alpine 12" subs in a sealed enclosure aimed toward rear of car, no ski pass hole - much louder but more rattle.

I have not tried the reverse polarity, will it do any harm to my amp or sub? My new JL 12W3V3 corner loaded sub sounds soft (powered by new JL 600/1 amp half way on the gain, crossed at 100Hz at 12db slope). Any advice appreciated. Is the reverse polarity for corner loaded enclosure - the common setup?

I was running 2 Alpine 12" subs in a sealed enclosure aimed toward rear of car, no ski pass hole - much louder but more rattle.

No harm at all, the sub works the same either way. To clarify, this is to eliminate cancellations at/near the crossover frequency, and the main purpose is to help with the integration of the sub with the mid bass frequencies coming from under the seats and to "hide" the true location of the sub. It will NOT make the sub sound louder!

When you try this, also drop the crossover frequency - 100Hz is too high, try 80.

I have not tried the reverse polarity, will it do any harm to my amp or sub? My new JL 12W3V3 corner loaded sub sounds soft (powered by new JL 600/1 amp half way on the gain, crossed at 100Hz at 12db slope). Any advice appreciated. Is the reverse polarity for corner loaded enclosure - the common setup?

I was running 2 Alpine 12" subs in a sealed enclosure aimed toward rear of car, no ski pass hole - much louder but more rattle.

If your sub is crossed at 12db slope, you ALREADY have a 180degree phase shift....no need to shift back

Ok, so filters will indeed create an an electrical phase shift at the crossover frequency. If the slope is 24db/oct the shift is 180 degrees, 12 db is 90 degrees. But normally there are two filters involved and the effect is cumulative. So while a 24db LPF on the sub creates a 180 deg shift, a matching 24db HPF on the underseats would also be 180 degrees, so the total effect would be 360 degrees, which would again mean zero phase shift. If the two filters were 12 db, then the phase shift would be 90 + 90 = 180 degrees. So, if the subwoofer and the mid bass were the exact same distance from the listener, then the 360 degree shift would result in no cancellations, while the 180 degree shift would result in massive cancellations (at the crossover point). However, the mid bass and sub are usually NOT the same distance from the listener. The difference in distance creates an acoustical phase shift. To remedy any potential cancellations at the listening position, due to electrical and/or acoustical phase shifts, one can simply try to reverse the polarity of the sub. This is explained in my "Scooby Doo" thread.

Ok, so filters will indeed create an an electrical phase shift at the crossover frequency. If the slope is 24db/oct the shift is 180 degrees, 12 db is 90 degrees. But normally there are two filters involved and the effect is cumulative. So while a 24db LPF on the sub creates a 180 deg shift, a matching 24db HPF on the underseats would also be 180 degrees, so the total effect would be 360 degrees, which would again mean zero phase shift. If the two filters were 12 db, then the phase shift would be 90 + 90 = 180 degrees. So, if the subwoofer and the mid bass were the exact same distance from the listener, then the 360 degree shift would result in no cancellations, while the 180 degree shift would result in massive cancellations (at the crossover point). However, the mid bass and sub are usually NOT the same distance from the listener. The difference in distance creates an acoustical phase shift. To remedy any potential cancellations at the listening position, due to electrical and/or acoustical phase shifts, one can simply try to reverse the polarity of the sub. This is explained in my "Scooby Doo" thread.